Thread resume for TSE-II 300B builders
Well I've been reading all the thread to extracy useful info, problems and suggestions regarding TSE-II building, thinking in a 300B.
Have been summing up all info in a OneNote file that is shared in attachement, simply rename .zip --> .one and magic is done.
Tips are copied from thread so there is a link to the exact page.
At the beginning I've put a copy of BOM Notes.
Hope it helps.....
Well I've been reading all the thread to extracy useful info, problems and suggestions regarding TSE-II building, thinking in a 300B.
Have been summing up all info in a OneNote file that is shared in attachement, simply rename .zip --> .one and magic is done.
Tips are copied from thread so there is a link to the exact page.
At the beginning I've put a copy of BOM Notes.
Hope it helps.....
I am also at the part of the checkout where I insert the rectifier. My B+ is way higher than I expected. My PT HV winding is 265-0-265V @ 130mA and my power supply is CLC: 47uF cap -> 40H 480 ohm choke -> 150uF cap. Modeling this in PSUD, I should be getting about 285V B+, but what I'm measuring across R30 is 365V. Any ideas why it would be so high? This is for a 45-based amp.
See post #19 and later...
https://www.diyaudio.com/forums/tubelab/346299-tubelab-se-ii-checkout-2.html#post6003067
https://www.diyaudio.com/forums/tubelab/346299-tubelab-se-ii-checkout-2.html#post6003067
Maybe I'm missing something, but you said your B+ was 372 with the rectifier plugged in... which is way too high for 45's as well. Even with all your tubes plugged in and your B+ went down to 339V, that's still too high. 45's should be operated around 275V, yeah?
Regardless, I still am not sure why my B+ is so high when PSUD reports I should be getting 285V.
"Tubelab- I blow stuff up so you don't have to."
Somewhere either on DIY Audio or the Tubelab website, Mr. Tubelab says he runs 45 tubes using B+ voltage ~375 or so.
All I can tell you is that I've been running my Tubelab TSE-II using 45 tubes everyday for at least 8 hours per day without any problems.
Keeping in mind I didn't build this amp to survive space flight or combat duty, it works and it sounds great. That's comparing it to the 10 other tube amps I have.
Now I'm not one of those people who has super sensitive ears, but I do know what good music sounds like. That's having raised two kids who are semi-professional musicians. They both have to have a full time job to make a living.
Somewhere either on DIY Audio or the Tubelab website, Mr. Tubelab says he runs 45 tubes using B+ voltage ~375 or so.
All I can tell you is that I've been running my Tubelab TSE-II using 45 tubes everyday for at least 8 hours per day without any problems.
Keeping in mind I didn't build this amp to survive space flight or combat duty, it works and it sounds great. That's comparing it to the 10 other tube amps I have.
Now I'm not one of those people who has super sensitive ears, but I do know what good music sounds like. That's having raised two kids who are semi-professional musicians. They both have to have a full time job to make a living.
No, I run my 45's at 315 to 325 volts. They are fine with that, but being old, I haven't pushed them beyond 330. That's all my 15 year old TSE will make when I have 125 volts of line voltage. It's usually around 120 to 122 volts, but I have seen 127, so maybe my 45's have seen a bit more voltage, but I didn't measure it then.
I do run my cheap (when I got them) Chinese 2A3's to 375 volts without issue. My current TSE-II is running a 300-0-300 volt Hammond 372HX that was intended for running 2 SPP boards at the same time. I get 375 to 390 volts of B+ with 2A3's or 300B's depending on line voltage and bias current. I have not tried 45's in this amp since the B+ is likely to be over 400 volts with 45's.
The B+ should be positive, and +431 volts is not out of line with only the rectifier tube installed. It will drop some when the 5842's are installed, and drop a lot more when the output tubes are installed and biased up.
If the B+ remains too high after adjusting to the desired bias current, replace C4 with a smaller cap. I have used as low as 4.7 uF in a board, to shed voltage but usually its 10, 22 or 33 uF.
The B- should be negative. I have seen voltages from -200 to -300 volts or more. The exact voltage does not matter. What is important is that the grid voltage at the output tube socket pin is negative, and adjustable by turning the bias pot. It should vary from around -20 V or so to - 90 V or so. Set it to the highest negative (-90 V) extreme before installing the output tubes.
That's why they call it DIY. Maybe it is 325 V.
It has to do with the power dissipated through the output tubes. How do you vary that? Use PSUD to calculate your component values.
With these Tubelab boards, if you follow the schematic and use the suggested components, you don't have to reinvent the wheel.
Calculate whatever values you think you need. Take your cut and move on. Tubelab already did the engineering work. I'm telling you that for my Tubelab TSE-II, it sounds great. That's all I care about. It hasn't burnt down the shop, it doesn't run blistering hot. It makes great sounding music.
It has to do with the power dissipated through the output tubes. How do you vary that? Use PSUD to calculate your component values.
With these Tubelab boards, if you follow the schematic and use the suggested components, you don't have to reinvent the wheel.
Calculate whatever values you think you need. Take your cut and move on. Tubelab already did the engineering work. I'm telling you that for my Tubelab TSE-II, it sounds great. That's all I care about. It hasn't burnt down the shop, it doesn't run blistering hot. It makes great sounding music.
I'm measuring ~2.487 V dc at output tube pin 1, ~324 at output tube pin 2, ~ -76.8 at output tube pin 3 and ~ 2.48 V dc at output tube pin 4.
That's using negative probe on ground and positive probe in the pins listed above. Rectifier and 5842 tubes installed.
That's using negative probe on ground and positive probe in the pins listed above. Rectifier and 5842 tubes installed.
Attachments
I'm not exactly reinventing the wheel here. I'm using a choke as suggested by the tubelab website, and I'm even using a PT with similar specs to the ones he used when getting 325V B+. And yes, all values were calculated with PSUD.
Thanks for that comment George! I didn't realize that the B+ would drop so much after the whole thing was set up. I got all the tubes in and biased the 45's, and now my B+ is sitting at 275V. Much better!